Hi there

You don’t need a backup battery in the autogate panel, it’s just there as backup in case of power failure

To me, its very worth the money for a Pi4. I managed to grab a 8GB model, somewhat future-proofing. To me its worth it cos it’s self contained, and i just keep it in my electrical riser/cabinet with active cooling (2 android box cooler fans running 4 hour shifts). It doesnt take up space, and it’s running headless. I just SSH into it now and then to update node.js and the plugins.

Homebridge just brings your non-homekit compatible devices into homekit. It’s my preferred choice, as i like to control everything in HomeKit cos of its simplicity. I only fall back on manufacturer’s apps if theres a fault.

Homeassistant is very powerful but to me kinda messy. You can bring many devices into home assistant and controlled within homeassistant. Homekit devices can br brought into homeassistant too. But if you are a tinkerer, you can dabble into HA, and then even Node-RED. I just don’t have that type of time anymore with work and kids.

Yup there is a Pi5 now, but i think it works the same, basically faster and more expensive.. haha. I just got the Pi4, with the power brick and usb cable. I didnt get the keyboard etc.

For the 4 hour shifts, its quite simple. I have 2 cooler fans (the android TV type), below the pi4. They are both powered via 5V1A usb adapters on separate wifi sockets. So, every 4 hours, one wifi socket turns on, the other turns off. This goes on every four hours. Before i installed these larger fans, i had the pi fan installed inside the Pi, and it brought the running temperature down from 90 degrees to 60 degrees. Still kinda how. Now with the larger fans, its running at 48 degrees. One day i probably will install larger fans. The cooler the better.

For homebridge, u just follow the guide to install onto your SD card or SSD (i use this as i read long term sd cards can fail). Then once u run it, u scan the homebridge QR code with your iphone and add it as a bridge into homekit. THen you go back to homebridge, and then install the ewelink plugin. The plugin will allow you to key in your ewelink credentials. You must have installed the ewelink autogate switch already inside the ewelink app. THe plugin will auto add the devices into homebridge, and thus, homekit.

Hmmm. Not able to sketch now but ill kinda list it out below, hopefully its easy to understand

1. Apple Home Hub (Apple TV or Homepod/Homepod Mini) - the main apple hub
1.a. Apple Homekit devices connected/controlled directly by the Home Hub e.g. Aqara, Tuya, (via their hub, or matter over thread or matter over wifi)

2. Homebridge via Pi4 connected to router using Lan cable
2.a Non compatible homekit devices brought into Homekit via homebridge plugins e.g. ewelink (sonoff), xiaomi, cctvs (dahua, hikvision etc via ffmpeg or cameraui or etc)

Hi there hmm
I made a diagram for you, but its not fully comprehensive, but should be easy enough to understand

Below is my setup. I use my iPhone/iPad/mac to control the smart home system via Apple Home app. I can also use Google Home or Alexa to control it, but it depends on which platform offers interplatform compatibility. Since i dont have a Google matter over thread border router, i cant control my curtains via google home. But essentially, brands like Tuya allow you to control your devices in Google/Alexa (mostly but not all).

But all in all, i can control the devices in
1. Apple Home app (my preferred choice)
2. Manufacturer app - Tuya app, Aqara App, Mi Home app, Ewelink App, etc
3. Google Home app - Some devices
4. Alexa App - some devices

No you need a homekit hub.. so cheapest way is homepod mini. All homekit hubs can also act as border routers

I got my homepod mini from Shopee it's much cheaper.

Also, to control the gate u just need a zigbee switch, like the one in my post above with a tuya homekit hub. Then you don't need to buy a pi5.